Due to a paucity of phonetic data, tone is usually ignored in theories of phonology or phonological acquisition although it is an essential component of the majority of the world's languages. This study examines Mandarin tone production in monosyllabic and disyllabic words by three- and five-year-old children via a picture naming task. The children's and their caregivers' productions will be filtered to eliminate lexical information. Judges will identify the tones based on the filtered speech. Children's accuracy rates will be compared to adults. Acoustic analysis will be performed to characterize children's tone productions. The specific aims are to determine developmental milestones of tone acquisition and to explore possible perceptual/articulatory constraints on tone/phonological acquisition. This will be the first study that systematically examines children's coarticulated tones and provides acoustic data on children's tone production. Results will expand our understanding of tone development, coarticulation development and the relation between speech motor development and phonological development. The findings will also have important implications for theories of phonological development and the evaluation and treatment of atypical speech development in Chinese children. [unreadable] [unreadable] [unreadable]